Method of producing grids for electron discharge devices



June 26, 1945-. J. w. EKSTEDT ET AL 2,379,135

METHOD OF PRODUCI-NG GRIDS FOR ELECTRON DISCHARGE DEVICES Filed Nov. 29, 1943 wim-Ax @Roc/wang of rnandrel and Welding jaws.

Patented June 26, 1945 METHOD F PRODUCING GRIDS FOR ELECTRON DISCHARGE DEVICES John W. Ekstedt, Union, and Albert F. Pltyo,

l Clifton, N. J.

Application November 29, 1943, Serial No. 512,168 1o calms.' (c1. 14o-71.5)

The present invention relates to a method of producing grids for electron discharge devices, such as radio tubes or the like..

An important object of the invention is to provide a method of the above mentioned character for utilizing a single set of spaced grid wires which are formed and attached to side rods.

A further object of the invention is to provide a method of the above mentioned character, for producing grids in succession, in a completed manner, except for stretching and sizing.

A fur-'ther object of the invention is to provide a method ci above mentioned character which will produce the grids quickly and economically.

A furtl'ier object of the invention is to provide a method or" the above mentioned character which is accurate and reliable in operation.

Other objects and advantages of the invention will be apparent during the course of the following description.

In the accompanying drawing, forming a part of this application and in which like numerals are employed todesignate like parts throughout 'the same,

Figure l is a side elevation of apparatus employed in the practice of the method, parts omitted,

Figure 2 is an end elevation of the same, taken on line2-2 of Figure 1,

Figure 2a is a horizontal section taken on line 2l-2 of Figure 2,

Figure 2b is a plan view of the cutting means forthe side rods,

Figure 3 is a view similar to Figure 2, parts broken away, showing a further step in the method, l

'Figure 4 isla similar view showing a further step,l

',lFigure isa similar view showing a further `is an' end elevation of the same, IFigure A9 1Sl albottom plan view of the grid, parts broken away,

Figure 10 is a bottom plan view of a slightly different form of grid, and f v1/Figure 11 is an end elevation of a modified form 1nthe drawing, wherein for the purpose of illustration is shown a preferred embodiment of apparatus used in the practice of the method, the numeral I0 designates a mandrel which is suit- 6 is a similar view showing a furtherably supported and is held stationary and preferably horizontally arranged. 'I'his mandrel is not bodily rotated. This mandrel includes segments II and I2,.and a reciprocatory tapered plunger I3. T he mandrel has a normal circum- .ferential size before the grid wires are bent or formed about the same, and after the grid is produced, the tapered plunger I3 is shifted t0- ward its large end so that the segments Il and I2 are radially collapsed, to permit of the removal of the grid from the mandrel. The segments I2 are provided in-their peripheries with longitudinal grooves I4, to receive the metal side rods I5, which are moved longitudinally therein. These grooves constitute a pair which are preferably arranged in a vertical plane, thereby holding the side rods I5 in a vertical plane.

The side rods are severed by a cutting means including reciprocatory blades I'I, and this cutting means is arranged near the discharge end of the stationary mandrel I0.

The side rods I5 are supported and guided into the grooves I4 and any suitable means is employed to eilect a step-by-step longitudinal feeding movement of the side rods.

The numeral I8 designates a single set of spaced grid wires, which may be paid out from a spool or drum and guided and fed longitudinally, in an intermittent manner, by any suitable means. The grid wiresl I8 pass through openings I8' in a stationary guide I9, forming one blade of a cutting device for the grid wires. This cutting device includes a coacting reciprocatory blade 20.

Arranged near and upon the discharge side of the guide I9 are jaws 2|, the lower ends of which are provided with downwardly tapering teeth 22, forming tapered openings or notches 23, between them. These notches are equi-distantly spaced and taper upwardly and receive therein the grid wires I8, and center and hold them. The two sets of teeth 22,01' the jaws 2l serve to arrange and hold the grid wires in equi-distantly spaced parallel relation. The jaws 2I are provided at their lower ends with beveled faces 24. The jaws 2I have curved faces 25, corresponding to the curvature of themandrel. The jaws 2I are carried by arms 26 and these arms are pivotally connected with each other by a pin 21 or the like, secured .to a vertically reciprocatory head v28. The arms 26 extend above the pivot 21 and carry rollers 29, to be engaged by a wedge 30, which is movable vertically with the head 28 and with relation thereto.

The numeral 3| designates carriages of upper and lower welding devices, which carriages are vertically reciprocated by any suitable means. Each carriage carries a pair of welding Jaws I! andl 3 8; which are rigidly attached to the carriage andfi'z'isulated therefrom and connected with the opposite poles of a source of welding current.

The practice of the method in connection with the apparatus herewith shown and described is as follows:

The jaws 2| are shifted to the uppermost position, Figures 1 and 2, and the side vrods Il are held within the grooves Il of the mandrel Il, the mandrel being then in the normal expanded condition. This mandrel is held stationary. The set of grid wires i8 are advanced a' step and then brought to rest, Figure 2. 4The grid wires are fed through the notches Il and over and in contact with the upper side rod i5 and the grid wires are then horizontally disposed and positioned at a right angle to the longitudinal axis o! the upper side rod. The teeth 22 of the Jaws 2| hold the grid wires in the set equi-distantly spaced and in parallel relation. The grid wires Il are now at rest and the next step in the method is to clamp the grid wires to the upper side rod Il, which is effected by bringing the carriage of the upper welding device downwardly toward the mandrel so that the upper welding jaws I2 and 33 clamp the grid wires to the upper side rod. The blade 2l of the cutting device is now moved downwardly and severs the leading portions of the grid wires. The severed grid wires now extend for equal distances upon the opposite sides of the upper side rod and are of the proper length to pass around the mandrel III, and their length is determined by the extent of the step-by-step feed movement oi' the set of grid wires. The severed grid wires are now being clamped to the upper side rod against displacement, and the Jaws 2l. while remaining open, are now moved downwardly, Figure 4, and exert a downward pressure upon the severed grid wires near their formed grid, Figure 6. The side rods Il are still within the grooves il and the side rods are now fed longitudinally a step, depending upon the desired length of the side rods, the formed grid being shifted longitudinally oi! of the mandrel, and the side rods are severed by the blades I1. This completes the cycle of operation of the method.

The produced grid now drops upon a conveyor or the like and is carried to an operator who may place the same upon a separate expansible mandrel, upon which the grid is stretched, shaped and sid.

In Figure 11, we have shown a slightly difierent form of mandrel and welding `laws. The segments I2 are shown as provided with insulating material 36, having grooves 4I'l formed therein to receive the side rods. Upper and lower welding jaws 3l' are provided. Each welding jaw 31' is connected with one pole of a welding source of current while the opposite pole is connected with the side rod. When the welding jaw 31' engages the grid wires it clamps the grid wires to the side rod and when the welding circuit is closed, the

ends and bend the severed grid wires downwardly l about the upper portion and sides of the mandrel Il. Figure 4. The jaws 2l continue to move downwardly and when they have reached the lowermost position, so that their curved faces 25 are in proper alignment with the mandrel, the wedge 3l is moved downwardly while the Jaws Il are held at the lowermost elevation, and the faces 25 form the lower portions oi' the severed grid wires about the lower portion of the mandrel, Figure 5. The carriage il of the lower welding device is now moved upwardly and the lower welding laws I2 and Il clamp the ends of the formed grid wires against the lower side rod The ends of each formed grid wire I8 preferably slightly overlap, although they may abut. 'Ihe welding circuits are now closed and the current passes from one welding jaw to the other, in each pair, and through the adjacent portion of the wires Il and side rod Il, and these wires are welded to each side rod. While it is preferred to delay the welding, until both welding devices clamp the grid wires to the side rods, yet the grid wiresv may be welded to the upper side rod i5 as soon as the upper welding device clamps the grid wires to the upper side rod, and the grid wires will then be subsequently welded to the lower side rod I5, when the lower welding device clamps the grid wires t'o the lower side rod. After the welding operation. the welding devices are moved from the mandrel Il and the jaws 2| are moved laterally from the mandrel and returned to the raised position, Figure 2, at which time the mandrel is collapsed to release the current passes from the welding jaw Il through the grid wires i8 and side rod to the opposite pole of the source of current. The welding Jaws 31 extend entirely across the set of grid wires, and the same is true of the welding jaws I2 and 33. All other parts oi' the apparatus remain identical with those shown and described in connection with the first form oi apparatus, and all other steps of the method remain identical with those described in connection with the first form of method.

'I'he invention is not restricted to the use of a circular mandrel nor the circularly curved faces 25, as these parts may be in diierent shapes depending upon the desired shape of the grid to be produced.

As shown in Figures 'l to 9, the grid produced includes side rods I5 and grid wires Il welded to the same. These grid wires are shown as circular, but the invention is not limited to this shape. The grid thus produced is subsequently placed upon an expansible mandrel and stretched, shaped and sized. The formed grid wires are accurately spaced and are parallel. The spacing of the grid wires and their number may be varied. as desired. The ends of each-grid wire Il slightly overlap, Figure 9, although they may be arranged to abut, Figure 10.

While we have shown the welding of the grid wires to the side rods, the grid wires may be secured to the side rods by notching or by any other suitable means.

It is to be understood that the form of our method herewith shown and described is to be taken as a. preferred example of the same, and that changes may be made in the order of the steps of the method, and in the steps, without departing from the spirit of the invention or the scope of the subjoined claims.

Having thus described our invention, what is claimed is:

1. The method of producing a grid for electron discharge devices, comprising supporting laterally spaced side rods upon a stationary mandrel and arranging them substantially diametrically opposite to each other, arranging a set of separate spaced substantially parallel grid wires which are separate from the side rods transversely of one side rod and bringing the intermediate portions of the grid wires adjacent t'o such side rod and extending the grid wires for substantially equal substantial distances upon opposite sides of such side rod, bending the end portions ot the grid wires about the stationary mandrel to form closed loops which surround the mandrel and bringing the opposite ends of the grid wires into the engagement with the other side rod, welding the intermediate portion of the grid wires to the adjacent side rod, and welding the opposite ends of the grid wires to the other side rod.

2. The method of producing a grid wire for electron discharge devices, comprising supporting side rods in laterally spaced relation upon a stationary mandrel and arranging the side rods in a substantially vertical plane, feeding a set of continuous spaced separate grid wires transversely over the upper side rod while holding the grid wires substantially parallel vand bringing the intermediate portion of the grid wires in contact with the upper side rod and extending the grid wires upon opposite sides of the upper side rod for substantial distances, clamping the intermediate portion of the grid wires to the upperv side rod, severing the grid wires at a point spaced from the upper side' rod so that the grid wires extends for substantially equal distances upon opposite sides of the upper side rods. engaging the grid wires upon opposite sides of the upper side rod and holding them properly spaced and forcing the grid wires downwardly into .engagement with the mandrel to form closed loops which surround the mandrel and bring the opposite ends of the grid wires into engagement with the lower side rod, clamping the opposite ends of the grid wires to the lower side rod, simultaneously welding the intermediate portion of the grid wires to the upper side rod and the opposite ends of the grid wires to the lower side rod, and removing the grid from the mandrel.

3. The method of producing a grid for electron discharge devices, the steps of supporting laterally spaced side rods upon a mandrel and holding the mandrel against rotation, substantially simultaneously feeding a continuous set of separate substantially parallel grid wires transversely across one side rod so that the grid wires extends for substantial distances upon opposite sides of such side rod and the grid wires has an intermediate portion adjacent to such side rod, then clamping the intermediate portions of the grid wires to the adjacent side rod, then severing Athe grid wires at a point spaced from such side rod, then substantially simultaneously bending the grid wires about the mandrel and bringing the opposite ends of the grid wires in contact with the other side rod, and then welding the intermediate portions of the grid wires to the adjacent side rod and the opposite ends of the grid wires to the other side rod.

4. In the method of producing a grid for electron discharge devices, the steps of supporting side rods upon a stationary mandrel and circumferentially spacing the side rods upon the mandrel so that they are laterally spaced, feeding a continuous set of spaced substantially parallel grid wires transversely across one side rod. so that the intermediate portions of the grid wires are adjacent to such side rod and the grid wires extend for substantial distances upon opposite sides of such side rod, holding the grid wires thus arranged against displacement in certain directions with relation to such side rod, then severing the grid wires at a point spaced from such side rod, then substantially simultaneously applying pressure to the' opposite end portions oi' the grid wires and bending the grid wires` around the rods stationary and generally parallel and laterally spaced. arranging a plurality of spaced separate grid wires which are separate from the side rods transversely of and adjacent to one side rod and bringing the intermediate portions of the grid wires into engagement with such side rod and causing the grid wires to extend for substantial distances upon opposite sides oi' such side rod, bending the opposite end portions of the grid wires about such s ide rod and mandrel for forming closed loops which surround the mandrel and bringing the opposite ends of the grid wires into engagement with the other side rod, and attaching the intermediate portions of the grid wires to the rst named side rod and the opposite ends of the grid wires to the other side rod.

6. The method of producing a grid for electron discharge devices, comprising supporting side rods upon a stationary mandrel for holding them stationary and generally parallel and laterally spaced, arranging a plurality of spaced substantially parallel separate grid wires which are separate from the side rods transversely of and adjacent to one side rod and bringing the intermediate portions of the grid wires adjacent to such side rod and causing the grid wires to extend for substantial distances upon opposite sides of such side rods, bending the opposite end portions of the grid wires about such side rod and mandrel while maintaining the grid wires substantially parallel for forming closed loops which surround the mandrel and bringing the opposite ends of the grid wires adjacent to the other side rod, attachl ing the intermediate portions of the grid wires to the first named side rod and the opposite ends of the grid wires tothe other side rod, and removing the assembled grid from the mandrel.

7. The method of producing a grid for electron discharge devices, comprising supporting laterally spaced side rods upon a. stationary mandrel and holding them generally parallel, arranging a. plurality of spaced separate grid wires which are separate from the side rods transversely of and adjacent to one. side rod and causing the grid wires to extend for substantial distances upon opposite sides of such side rod while holding the separategrid wires substantially parallel, clamping the intermediate portionsjof the grid wires to the first named side rod, bending the end portions of the grid wires about the rst named side rod and mandrel for forming closed loops which surround the mandrel and bringing the opposite ends of the grid wires adjacent to the other side rod, attaching the intermediate portions of the grid wires to the irst named side rod and the opposite ends of the grid wires to the other side rod, and removing the assembled grid from the mandrel.

8. The method of producing a grid for electron discharge devices, comprising supporting laterally spaced side rods upon a stationary mandrel, moving a single set of spaced separate grid wires which are separate from the side rods transversely across one side rod while maintaining the grid wires substantially parallel and bringing the intermediate portions of the grid wires adjacent to such side rods, clamping the intermediate portions o! the grid wires to the adjacent side rod, severing the grid wires at a point spaced from such side rod so that the grid wires extend upon opposite sides of such side rod for substantial distances, substantially simultaneously bending the end portions o! the severed grid wires about the mandrel to Iorm closed loops surrounding the mandrel and bringing the opposite ends of the grid wires adjacent to the other side rod, attaching the grid wires to the side rods, and removing the assembled grid from the mandrel.

9. The method of producing a grid for electron discharge devices, comprising supporting laterally spaced side rods upon a mandrel. moving spaced separate grid wires which are separate from the side rods longitudinally so that they extend transversely across one side rod and have their leading ends spaced from such side rod, clamping the grid wires to such side rod, severing the grid wires at a point spaced from such side rod so that the grid wires extend for substantial distances upon opposite sides of such side rod, bending the end portions of the grid wires about the mandrel to form closed loops which surround the mandrel and bringing the opposite ends oi' the grid wires adjacent to the other side rod, attaching the grid wires to the side rods, moving the side rods longitudinally to shift the formed grid from the mandrel, and severing the side rods to separate out the formed grid.

10. The method of producing a grid for electron discharge devices, comprising holding laterally spaced side rods upon a stationary mandrel having a normal selected diameter, moving a set o! spaced separate grid wires which are separate from the side rods longitudinally so that they extend transversely across one side rod while holding the grid wires substantially parallel and arranging their intermediate portions adjaoent to such side rod so that the grid wires project bevyond such side rod for substantial distances.

clamping the grid wires to such side rod. severing the grid wire and a point spaced from such side rod, bending the end portions oi' the severed grid wires about the mandrel to form closed loops which surround the mandrel and bringing the opposite ends of the grid wires adjacent to the other side rod.attaching the intermediate portions of the grid wires to the first named side rod and their opposite ends to the other side rod, collapsing the mandrel to free the formed grid for longitudinal movement, moving the side rods longitudinally to shift the formed grid from the mandrel, and severing the side rods to separate out the formed grid.

JOHN W. EKBTEDT. ALBERT F. PITYO. 

